Pirelli Cavi E Sistemi S.p.a.

Gianluca Gobetti

Sergio Bosso

Claudio Zammarchi

Massimo Notargiacomo

Giuseppe Ravasio

Franco Mussino

Emilio Casaccia

The present invention relates to a method and to a signal predistorter circuit for eliminiating the nonlinearities in the input/output characteristics of nonlinear stages, in particular for eliminating the third-order nonlinearities. More particularly, it relates to a method and to a predistorter circuit for external optical modulators of television signals. The method for predistortion of a signal of variable amplitude comprises the phases of: delivering the said signal to at least one first distorter circuit; biasing the said at least one first distorter circuit; distorting the said signal in the said at least one first distorter circuit; characterized in that the said phase of biasing the said at least one first distorter circuit comprises the phase of maintaining a substantially constant preset voltage value on varying the amplitude of the said signal at the said at least one first distorter circuit.

External optical modulation system comprising a predistorter

An optical modulator includes an optical waveguide and an electrode structure coupled to the waveguide such that a modulating signal applied to the electrode structure varies the refractive index of the waveguide so as to produce a modulated optical output signal. The electrode is fabricated in the form of a transmission line terminated in a short circuit. The ratio of the wavelength of the modulating signal to the effective length of the electrode is comprised between 2.1 and 4.0, and is preferably of approximately 2.7. The modulator can be constructed to provide either phase or amplitude modulation. An optical transmission method having SBS suppression and an optical modulator system are further provided.

Narrow-band optical modulator with reduced power requirement

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Castelvetro Piacentino, Italy

Gianluca Gobetti